WELD MEDIUM FOR DISSIMILAR MATERIALS
An example of a door curtain having pieces comprised of different thermoplastic materials includes a weld medium that facilitates the welding of two thermoplastics that are otherwise not readily welded together. In some examples, the weld medium comprises two outer layers that are joined to each other, wherein one layer is of the same polymer as one of the curtain pieces, and the other opposite layer is made of the same polymeric material as that of the other curtain piece. The weld medium is sandwiched between the two curtain pieces such that matching materials of the curtain and weld medium face each other. The two curtain pieces, with the weld medium between the two, are then thermally or ultrasonically welded together. The weld medium can be made by coating a fabric sheet with the two different plastic layers bonded to opposite sides of the fabric sheet.
This patent generally pertains to welding of plastic sheets and, more specifically, to a weld medium for such a process.
BACKGROUNDVertical operating doors often include a roll-up curtain for opening and closing the door. Other types of doors have curtains that operate in a translating and/or folding manner. In any case, door curtains can be made of various materials such as vinyl, polyurethane or polypropylene. Each material has its advantages and disadvantages.
Polyurethane, for example, has very good wear properties but is expensive and subject to UV deterioration. Vinyls have good UV properties but tend to get stiff and brittle at low temperatures. Polypropylene has good weather resistance and is relatively inexpensive, but it has relatively poor wear resistance.
Certain examples are shown in the above-identified figures and described in detail below. In describing these examples, like or identical reference numbers are used to identify the same or similar elements. The figures are not necessarily to scale and certain features and certain views of the figures may be shown exaggerated in scale or in schematic for clarity and/or conciseness. Additionally, several examples have been described throughout this specification. Any features from any examples may be included with, a replacement for, or otherwise combined with other features from other examples.
While different materials are available that have advantages and disadvantages, it is difficult to create a single door curtain with a broad range of ideal qualities.
To meet various design needs, the illustrated examples of curtain 12 is comprised of three different sheets of material, as shown in
Although the various sheets of curtain 12 could be sewn together, it can be awkward sewing large, cumbersome sheets of material. Moreover, the resulting seams can be vulnerable to wear, and the seams may create crevices that tend to harbor mold and bacteria. Thus, the sheets 26, 28 and 30 of curtain 12 preferably are welded to each other by way of ultrasonic vibration or heat. Sheets of certain dissimilar materials, however, are not always readily weldable to each other because of their different material properties. Sheets of dissimilar materials are referred to herein by the term “distinguishable materials.” The term, “weld” means melting at least the surface of two proximal pieces so that the two pieces become joined (i.e., connected or coupled to each other) and/or molecularly bonded.
Referring to
A second weld medium 38 is used for joining the first sheet 26 (e.g., main polypropylene sheet) to a third sheet 30 (e.g., a polyurethane sheet). The second weld medium 38, however, has a first layer 40 comprising polyurethane for welding to the polyurethane sheet 30 and an opposite-side layer 42 comprising polypropylene for welding to the main polypropylene sheet 26. To join other combinations of sheet materials, different weld media can have different types of layers, such as polyurethane and vinyl, or just about any other imaginable combination of two thermoplastic materials.
For the examples illustrated in
In
To ensure bonding among granules 60′ and 62′, it may be desirable to add a suitable binder or adhesive to the granule mixture prior to compressing and/or applying heat to the granules 60′ and 62′ as shown in
In another example, shown in
At least some of the aforementioned examples include one or more features and/or benefits including, but not limited to, the following:
In some examples, two sheets of two different thermoplastic materials are welded to each other by way of weld medium that includes a layer of each of the two materials.
In some examples, the weld medium's two layers are joined to each other by way of an intermediate layer.
In some examples, the weld medium's two polymeric layers melt at a temperature that is below a combustion temperature at which the intermediate layer can bum, thereby rendering the weld medium suitable for welding sheets made of the same materials as the weld medium's layers.
In some examples, the weld medium's two layers smoothly blend from one material at one layer to a second material at the other layer.
In some examples, the weld medium's two layers are comprised of intertwined strands, wherein each layer is partially exposed to the opposite layer's side.
In some examples, the weld medium joins a polypropylene sheet to a vinyl sheet.
In some examples, the weld medium joins a polypropylene sheet to a polyurethane sheet.
In some examples, the weld medium joins a polyurethane sheet to a vinyl sheet.
In some examples, the weld medium provides a sealed joint that is particularly suitable for a door curtain used in a food related environment.
Although certain example methods, apparatus and articles of manufacture have been described herein, the scope of the coverage of this patent is not limited thereto. On the contrary, this patent covers all methods, apparatus and articles of manufacture fairly falling within the scope of the appended claims either literally or under the doctrine of equivalents.
Claims
1. A plastic weld joint, comprising:
- a first sheet comprising a first polymer;
- a second sheet comprising a second polymer, wherein the first polymer includes a material property that is distinguishable from that of the second polymer; and
- a weld medium comprising a first layer joined to a second layer, the first layer includes the first polymer, the second layer includes the second polymer, the first layer is molecularly bonded to the first sheet, and the second layer is molecularly bonded to the second sheet.
2. The plastic weld joint of claim 1, wherein there is more of the first polymer in the first layer than in the second layer.
3. The plastic weld joint of claim 1, further comprising an intermediate layer that joins the first layer to the second layer.
4. The plastic weld joint of claim 3, wherein the intermediate layer is comprised of a fabric.
5. The plastic weld joint of claim 3, wherein the first polymer and the second polymer melt at temperature that is below a combustion temperature at which the intermediate layer can burn.
6. The plastic weld joint of claim 1, wherein the first and second layers include a plurality of intermingled strands.
7. The plastic weld joint of claim 1, wherein the first polymer includes vinyl and the second polymer includes polypropylene.
8. The plastic weld joint of claim 1, wherein the first polymer includes vinyl and the second polymer includes polyurethane.
9. The plastic weld joint of claim 1, wherein the first polymer includes polyurethane and the second polymer includes polypropylene.
10. The plastic weld joint of claim 1, further comprising a door curtain comprised of at least one of the first sheet and the second sheet.
11. A method of joining two dissimilar sheets, the method comprising:
- positioning a first sheet in proximity with a second sheet, wherein first sheet includes a first polymer, and the second sheet includes a second polymer having a material property that is distinguishable from that of the first polymer;
- inserting a weld medium between the first sheet and the second sheet, wherein the weld medium comprises a first layer and a second layer joined to each other, the first layer includes the first polymer, and the second layer includes the second polymer;
- welding the first layer to the first sheet; and
- welding the second layer to the second sheet, thereby joining the first sheet to the second sheet via the weld medium.
12. The method of claim 11, wherein welding the first layer to the first sheet and welding the second layer to the second sheet are performed substantially simultaneously.
13. The method of claim 11, wherein welding the first layer to the first sheet and welding the second layer to the second sheet are performed by way of ultrasonic vibration.
14. The plastic weld joint of claim 11, wherein the weld medium includes an intermediate layer that joins the first layer to the second layer.
15. The plastic weld joint of claim 14, wherein the intermediate layer is comprised of a fabric.
16. The plastic weld joint of claim 11, wherein the first polymer includes vinyl and the second polymer includes polypropylene.
17. The plastic weld joint of claim 11, wherein the first polymer includes vinyl and the second polymer includes polyurethane.
18. The plastic weld joint of claim 11, wherein the first polymer includes polyurethane and the second polymer includes polypropylene.
19. A method of creating a door for a doorway, the method comprising:
- positioning a first sheet in proximity with a second sheet, wherein first sheet includes a first polymer, and the second sheet includes a second polymer having a material property that is distinguishable from that of the first polymer;
- inserting a weld medium between the first sheet and the second sheet, wherein the weld medium comprises a first layer and a second layer joined to each other, the first layer includes the first polymer, and the second layer includes the second polymer;
- welding the first layer to the first sheet;
- welding the second layer to the second sheet, thereby joining the first sheet to the second sheet to create a door curtain; and
- moving the door curtain across the doorway.
20. The method of claim 19, wherein the weld medium includes an intermediate layer that joins the first layer to the second layer.
21. A plastic weld joint, comprising:
- a first sheet comprising a first polymer;
- a second sheet comprising a second polymer, wherein the first polymer includes a material property that is distinguishable from that of the second polymer; and
- a weldable medium comprising the first polymer and the second polymer, wherein the concentration of the first and second polymers varies across at least one cross-section of the weldable medium, such that the weldable medium has an orientation in which a portion of the weldable medium has a sufficient concentration of the first polymer to enable it to be molecularly bonded to the first sheet.
22. A method of joining two dissimilar sheets, the method comprising:
- positioning a first sheet in proximity with a second sheet, wherein first sheet includes a first polymer, and the second sheet includes a second polymer having a material property that is distinguishable from that of the first polymer;
- orienting a weld medium comprising a first polymer and second polymer that vary in concentration across at least one cross-section of the weld medium so that a portion of the weld medium having a relatively higher concentration of the first polymer contacts the first sheet;
- bridging the first sheet and second sheet with the oriented medium;
- welding the portion of the weld medium having the relatively high concentration of the first polymer to the first sheet.
Type: Application
Filed: Mar 2, 2009
Publication Date: Sep 2, 2010
Inventors: Carl David Hardison, III (Preston, IA), Peter S. Schulte (East Dubuque, IL), Thomas Jansen (Dubuque, IA)
Application Number: 12/396,094
International Classification: F16B 5/08 (20060101); B31B 1/60 (20060101); B29C 65/06 (20060101);